Welding electrode



Oct. 30, 1945. J HQEH 2,387,905

WELDING ELECTRODE Filed May 15, 1944 Patented Oct. 30, 1945 WELDINGELECTRODE Joseph Hceh, Congress Park, 111., assignor to WitlekManufacturing 00., Chicago, 111., a corporation of Illinois ApplicationMay 15, 1944, Serial No. 535,718

6 Claims.

This invention generally relates to resistance welding which involvesthe passage of an electric "current through the adjacent portions of themetallic members to be welded. Heat is generat- ;.ed at the pointsofcontact where the greatest resistanceto the flow of the current isencountered while pressure is applied to force the members together andform the weld.

More particularly, the present invention relates to electric-resistancewelding of the type 'know-n'as spot welding and has specific referenceto a new and improved welding electrode for use .in spot welding.

Electric resistance welding involves numerous engineering problems suchas regulating the mechanical pressure and rate of advance of the partstoward one another at various stages of the process of heating the metalat the surfaces of contact, arresting the process at the proper instant,and the regulation of the current to the most suitable amount at allstages of the process; however, my invention is directed to theimprovement of the spot welding electrodes to thereby overcome certaindisadvantages in presently employed electrodes and to enhance andfacilitate spot welding operations.

My improved electrode is particularly adapted to spot welding ofmetallic members, sheets or strips of thin gauge, such as flexiblemetallic strips-employed in hose clamp bands wherein portions of samearewelded to other portions thereof or wherein the ends thereof areconnected together.

I have'found that in spot welding hose clamp bands the use of electrodeshaving pointed, rounded, or spherically shaped tips results in excessiveflashing and formation of oxides and the attendant dischargeof finemolten metal. In certain operations of hose clamp manufacture, as

where the ends of aclamp band are provided with perforations for passagetherethrough of the band-tightening screw and which band ends arewe'lled to a threaded nut with said perforations aligned with thethreaded opening in the nut,

welding with a pointed electrode causes a discharge of molten metalparticles and oxides into the threaded opening within the nut and thusrequiring the retapping of the nut. Furthermore, I have found in suchparticular clamp manufacture that where a pilot depends below anundivided fiat welding face of a spot welding electrode, that where thefiat contact face is not ventilated or provided with a transverse slot,some of the discharged metal particles or oxides become deposited on andattached to the flat contact face of the electrode as well as the pilotwith the disadvantage that the electrode contact face and pilot'mustfrequently be refinished or cleaned to remove such deposits.

It -is therefore an object of my invention to provide an electrode ofnovel construction which will overcome the above-recited disadvantagesof present spot welding; such novel electrode construction including theadaptation of the contact face of the electrode to the welding togetherof metal strips or sheets which are provided with, prefer-ably integral,protrusions on one or both of the opposed faces of the strips or sheetsto be welded together and such adaptation including the provision of afiat contact face having at least one slot disposed across such fiatface; and

where clamp band ends having aligned perforations for the tighteningscrew are welded to a nut having a threaded opening in register withsaid perforations, then such adaptation preferably includes a pilotprojecting downwardly from the slot in the contact face to a point belowthe plane of such flat contact face.

Among other objects of my invention is to provide a new and improvedelectrode which is particularly adapted for spot welding one or moremetallic members to another metallic part where one or more of saidmembers, or said part, are provided with one or more integralprotrusions through which the welding current is concentrated in itsflow between a pair of opposed electrodes to thereby produce an improvedspot-welded connection of said one or more members to said part.

Another object of my invention is found in the provision of novel spotwelding electrodes which are provided with fiat contact faces adapted tospot weld one or more metallic members to another metallic part atspaced spots or areas where said one or more members are formed withintegral protrusions through which protrusions the l flow of the currentbetween the flat faces of the electrodes is concentrated to produce aplurality of spaced spot welds disposed within the areas of the fiatfaces of the electrodes.

Another object of my invention resides in the provision of a preferablyhollow water-cooled spot welding electrode having a fiat but slottedcontact face dividing such contact face into spaced fiatpressure-exerting and current conducting areas adapted to be positionedover predetermined protrusions of the members to be welded, eachprotrusion being substantially equal in area to the area of the spotweld desired thereat.

Still another object of my invention is found in the provision of a spotwelding electrode having a flat but slotted contact face which isparticularly adapted for spot welding overlapped ends of a hose clampband to a threaded nut, and which ends are frequently provided withaligned perforations for the band-tightening screw and also are providedwith one or more integral protrusions adapted, upon compression betweenthe electrodes and the simultaneous passing of an electric currenttherethrough, to form the desired spot welds whereby the ends of theclamp band are securely welded to the threaded nut; such electrode beingpreferably provided with a fiat slotted contact face and with a pilotwhich depends from the slotted portion of the electrode downwardly belowthe plane of its flat contact face and which pilot functions to assistin retaining the perforated band ends in proper relative alignment oneto the other and to the threaded opening in the nut and also functionsto keep the threads in the nut substantially free from particles ofmolten metal and oxides incidental to the electrical flash at the momentof welding.

My invention is herein preferably exemplified in the welding operationemployed to secure overlapped ends of a flexible metal band to athreaded nut such as the band and nut employed in the construction of ahose clamp shown in patent appplication Serial No. 516,121 filed byBenjamin A. Tetzlaff, however, my improved electrode is obviously notlimited to welding of hose clamp bands but may be used for Welding oneor more metallic members to another metallic member or part where one ormore of said members, or said part, are provided with one or more,preferably integral, protrusions disposed between adjacent faces of suchmembers being welded, said protrusions cooperating with the flat contactfaces of the electrodes for concentrating the flow of the electriccurrent through such protrusions while pressure is simultaneouslyexerted by the electrodes to heat and collapse such protrusions tothereby cause a spot welding of said members thereat.

In the drawing:

Fig. 1 is a side elevation of a hose clamp band having overlapping endsprovided with integral protrusions and which overlapped band ends areadapted to be welded to a nut by my improved electrodes;

Fig. 2 is a plan view of Fig. 1;

Fig. 3 shows a side elevation of my improved electrodes during theproces of welding the overlapping ends of the clamp band to the nutshown supported on the lower electrode;

Fig. 4 is an end elevation of the electrodes and clamp band shown inFig. 3 with a portion of the clamp band broken away to show the lowerelectrode;

Fig. 5 is a vertical section through an upper electrode embodying myinvention taken on line 5-5 of Fig. 3;

Fig. 6 is a vertical section through the tip end of the electrode takenat a right angle to the section shown in Fig. 5;

Fig. 7 is a horizontal cross-section taken on line 'II of Fig. 6; and

Fig. 8 is a perspective view of the electrode shown in Figs. 5, 6 and 7but in reduced scale and in inverted position to show more clearly thetransverse slot.

In the illustrations, the clamp band I0 consists of a strip of flexiblemetal formed to provide a substantially circular medial portion IDhaving converging portions I 0 provided with lat ra ly the clamp bandshown in bent overlapping portions I I1 terminating in bent tabs IIB Theoverlapped portion Ill are provided with central perforations HI forpassage therethrough of a band-tightening screw (not shown herein) andwhich screw is adapted to be threaded into the nut II, shown in Figs. 3to 7 inclusive, and to which nut II the overlapped ends I 9 are weldedwhen the clamp band is finally assembled.

Since this specification is directed to electrode improvements and notto a hose clamp which is used in the illustrations simply as aconvenient way to illustrate the operation of m improved electrodes,only the clamp band and the nut elements of the hose clamp are shown inthe attached drawing.

Prior to the welded connection of the nut I I to the overlapped band endportions III these portions IG are die-stamped while in overlappedposition to provide pairs of nested protrusions I0 which are moreclearly seen in Fig. 5.

My improved electrode as preferably shown in Figs. 5 to 8 inclusiveconsists of an elongated body I3 made from any suitable material chieflyof copper or copper alloy having a hollow exteriorly threaded upperportion I 3 adapted for threaded connection with a movable electriccurrent conductor arm of welding apparatus, the cavity I3 being adaptedto receive therein a cooling fluid such as water.

The lower or operative tip portion I3 is provided with a flat horizontalface or flat contact end I3 which is divided by at least one slot orrecess I 3 extending transversely across the contact end into the bodyof the electrode to thereby divide the contact end into a pair of spacedcontact faces I3 The cooperating lower electrode I4 is provided with aflat horizontal upper contact face M which is parallel to the contactfaces I3 of the upper electrode I3 and the face M is preferably formedslightly depressed below a pair of parallel narrow upstanding integralside stripportions M for facilitating the retainment of the nut IItherebetween when positioned upon the lower electrode I4.

Assuming that the clamp band I 0 shown in Figs. 1 and 2 is not providedwith the perforations I 0 but that it i formed as otherwise shown withthe protrusions IO the overlapped end portions I0 may be readily spotwelded to one another and to the nut II by mounting the nut I I 'uponthe lower electrode I4, then inserting the band I0 over the lowerelectrode so that the overlapped portions I6 are positioned upon the nutII, as shown in Fig. 3, and then causing a movement of the electrodestoward one another to forcibly and with proper pressure engage theoverlapped portions III and nut II between the electrodes while electriccurrent is caused to flow between the electrodes in concentrated pathsthrough the protrusions I U while such protrusions due to the appliedpressure and heat collapse and form clean spot welds to thereby securethe overlapped portions IIJI to the nut II. In such operation, the spotwelds are produced by the pair of flat contact faces I3 in a simple andefiicient manner and any accompanying flash and discharge of moltenparticles or oxides passes outwardly from the electrode through the endsof the slot 13*, in

fact, the use of my improved transversely ventilated flat faced spotwelding electrode operates to quench the usual incidental flash tothereby reduce same and the oxides to a minimum.

My improved upper electrode is particularly adapted for spotwelding itheoverlapped ends 10 of the clamp band tlifl'toamut ;l;| -:-asillustratedzin Figs. 1 to ezinclusive'where such zoverlapped lends LDare provided'with:the'perforations which must register with the"threaded opening :in ithe nut 1:1. "To facilitate suchweldingioperation, the electrode body :13 is provided, in the lower tipportion 13, with a central cylindrical bore 13 which "extends :at itsupper end into the cavity 13 but isiclosed at its-upper endwithiarremovable iplug orsocket screw 15 to preventflow :of thecooling'fiuidlintothe bore 11 3*.

At its .lower end, :the bore 13 .communicates with a cylindrical bore513 whichis preferably larger in diameter than the :bore 4-3 andxpreferahly of .a diameter equal to the width .of the slot 13 The .slot13 extends transversely .of the electrode contactlend 13 .and' is open:at .such end 13 to provide-the spaced :fiatconta'c'tzfaces 1 3 A pilot1'5 preferably :made of hardened steel having a shank 115itightly'fitted into :an insulation sleeve or fiber bushing 1'1 issecurely-mounted in the bore 23 in such position that the upper end ofthe bushing 1'1 is supported in abutment 1 with tl e shouldered upperend of the bore 13 and itsilower end is aligned with the upper face ofthe slot 13 and so that the operative head 1 G of the pilot it dependsbelow the electrode contact faces 13 As more clearly seen in 'Figs. to 8inclusive, the pilot head 16 is slightly widened in one transversedirection to :extendbeyond the shank 16 for hearing against thelowerencl of the=bushing 1 1 and to provide a pair of flatopposed side 1faces 18; the head 16 being preferably formed with a curved lower edgeand of less thickness, transversely to the side faces 1 5,than-thediameter of the shank 16 Assuming that the clamp band 113 isprovided with the perforations 113 and with the protrusions '10 in theoverlapped end portions 13, as shown in Figs. 1 and 2, the overlappedend :portions 10 may be spot welded to one another and to the nut 11 bymounting the .nut 11 upon the upper face M .of the lower electrode 14,then placing the band end portions 10 in overlapped position upon thenut 1 1, as shown in Fig. 3, and then causing a movement of the upperelectrode 13 downwardly to forcibly, and with the proper pressure,engage the overlapped portions 10 and nut 11 between the electrodeswhile electric current is caused to flow between the electrodes throughspaced paths defined by the protrusions During momentarily appliedpressure and under the heat produced b the concentrated flow of electriccurrent between the electrodes through the protrusions 10 theprotrusions 1G will collapse and form spot welds within the areas ofsuch protrusions to thereby securely spot weld the overlapped portions10 to the nut l1.

Just prior to such spot welding operation and during the movement of theupper electrode toward the lower electrode, the head 16 of the pilot 16will pass into the clamp band perforations 10 and preferably partiallyinto the threaded opening in the nut I 1 just at the moment when theflat electrode contact faces 13 engage the upper one of the overlappedband portions 10 and the relative positions of the pilot head 15 bandportions 10, and nut 1 l at such moment of contact are illustrated inFigs. 5 and 6 and, from such illustrations, it will be apparent that theprotrusions 10 constitute defined and restricted :paths for :the flowofthe-electriccurrent through the overlapped band portions 10 and the nutH and that, under pressure applied through the flat contact faces Iliiand the heat generated by th'e electric current, such protrusions 10readily collapse and form the desired spot welds whereby the overlappedband end portions I'B -are securely spot welded to the nut H by myimproved flat tacedelectrode.

Among the advantages attained by my improved spot welding electrodethrough its novel structural features such as the fiat contact faces 215 the ventilation provided by the transverseslot or recess i3, and thepilot it are the following:

on A substantial reduction in the incidental welding flash;

(b) A substantial reduction in the accompany-- ing discharge of moltenmetal or oxides;

(c) The advantageous results attained-through the combination of thetransverse ventilating slot and pilot whereb the pilot functions as aloc-ator for the electrode to guide it into proper contact positioningupon and over the indentations 1U of the overlapped hand portions andwhereby the pilot also functions as a fender or director of the weldingflash and the accompanying discharge of molten metal or oxides away fromthe threaded opening in the nut I I through the open ends of the slot 13thus fending and protecting the threads in the nut H from impingementthereon of particles of molten metal;

(d) Increased efficiency in spot welding operations through thesimultaneous welding of multiple spots;

(e) Increased efliciency through elimination of the operation ofretapping of the threads in the nut H; and

(f) Reduction in costof maintenance of a clean contact face of theelectrode by the reduction of the welding flash and accompanyingparticles of fine molten metal and the forceful discharge of suchreduced quantit of particles of molten metal through the ventilatingslot whereby the electrode tends to be self-cleaning.

'It may be noted that my improved faced electrode is particularlyadapted to spot weldi g of members or parts which are provided withpreferably integral offset protrusions such as. for example, theprotrusions 11! shown die-stamped into the overlapped portion MI of theclamp band Iii in Figs. 1 and 2. The vertical center-line of suchprotrusions W being disposed perpendicularly to the horizontal plane ofthe flat contact face of the electrode. Obviously, spot weldingoperations can readily be performed with my flat faced electrode wheresuch members or parts to be welded are not provided with integralprotrusions, such as the protrusions i-J as in lieu of such protrusionssuitable small metallic discs or washers may be interposed between themembers and parts to be spot welded thereat.

To increase the ventilation through the slot 13*, I prefer to make thetransverse thickness of the pilot head E3 of less width than the widthof the slot.

From the above description and attached drawing it will be readilyapparent that my improved electrode is particularly adapted tooperations where multiple of spot welds are desired to be simultaneouslyperformed in one operation as in spot welding one or more metallicmembers to another metallic part where one or more of said members orsaid part are initially, prior to welding, slightly separated by one ormore metallic spacer formations, or spacer protrusions formed integrallywith said formations one or more of said members or said part, andthrough which spacer formations or protrusions the welding current isconcentrated in its flow between the electrodes to thereby effect a spotWelded connection of said one or more members to said part by combinedpressure and fusion of or protrusions.

I claim:

I 1. A spot welding electrode having a fiat workengaging end providedwith a slot dividing said work-engaging end into a pair of spaced flatplane-aligned spot welding contact faces, and a pilot mounted in theelectrode and extending through said slot outwardly from the electrodebeyond said plane-aligned contact faces, said pilot being electricallyinsulated from the body of the electrode. I

2. A spot welding electrode having a flat workengaging end provided witha slot dividing said work-engaging end into a pair of spaced flatplane-aligned spot Welding contact faces, and a pilot removably mountedin and electrically insulated from the body of the electrode andextending through said slot outwardly of the workengaging end beyond theplane of said contact faces, said pilot being of less width than saidslot.

3. A spot welding electrode comprising an elongated vertically disposedbody having a cavity therein for a cooling fluid, a bore within saidbody below said cavity, said body having a flat workengaging end, a slotdisposed transversely of the electrode body dividing said work-engagingend into a pair of spaced plane-aligned spot welding contact faces, saidbore extending at its upper end into communication with said coolingfluid cavity and at its lower end into communication with said slot,removable closure means closing communication between said cavity andsaid bore, and a pilot removably end of said bore, means in ing saidpilot electrically from the body of the electrode, said pilot being ofless Width than said slot and extending downwardly through said slotbeyond the plane of said spaced contact faces.

said bore for insulat- 4. A spot welding electrode as defined in claim3, said bore having a diametrically enlarged lower end portion, saidinsulating means comprising a "sleeve of insulating material securelyengaging end portion of said pilot, and said pilot having a headslightly wider, longitudinally of said slot, than the said upper endportion thereof which is secured within said sleeve and the lowerportion of said head terminating in a plane spaced from the plane ofsaid contact faces.

5. In spot welding apparatus including an upper electrode and a lowerelectrode adapted for simultaneously spot welding a pair of overlappedend portions of a circular metallic clamp band to a face of a nut havinga threaded opening therein, said overlapped end portions each beingprovided with a perforation in alignment with the opening in said nutand each having integral protrusions so arranged that the protrusions ofone of said portions are nested in the protrusions of the other one ofsaid portions and through which protrusions the welding current isconcentrated in its fiow between the electrodes to thereby eifect a spotwelded connection of said overlapped end portions to said nut bycombined pressure and fusion of said protrusions, said lower electrodehaving a fiat work-supporting contact face, said upper electrode havinga fiat work-engaging end Provided with a transverse slot dividing saidworkengaging end into a pair of spaced plane-aligned spot weldingcontact faces, and a pilot mounted in said Work-engaging end of theupper electrode, electrically insulated therefrom, extending throughsaid slot beyond the plane of said'aligned contact faces to therebypermit said pilot to enter said aligned perforations of said overlappedend portions and the threaded opening of said nut prio to the pressureengagement welding operation of said overlapped band end portions tosaid nut by said electrodes.

6. A spot Welding electrode having a slotted work-engaging end dividedinto a plurality oi spaced fiat spot welding contact faces, and a pilotmounted in and electrically insulated from the body of the electrode andextending through the slotted portion of the electrode outwardly beyondsaid contact faces.

therein the upper JOSEPH HOEH.

